function dl_a_day_traffic(datename, filedir)

% date: which date's file to download; format: yyyymmdd, example '20110704'
% filedir: where to place the downloaded data file

% wget is required
% -q: silent mode
% -P: save to different directory, specified by 'filedir'
yr = datename(1:4);

cmd = sprintf('wget -q -P %s http://tcfreeways.itslab.umn.edu/data/traffic/rawbin/%s/%s.traffic', filedir, yr, datename);
system(cmd);